How to get the row top 1 in Spark Structured Streaming?

I have an issue with Spark Streaming (Spark 2.2.1). I am developing a real time pipeline where first I get data from Kafka, second join the with another table, then send the dataframe to a ALS model (Spark ML) and it return a streaming dataframe with one additional column predit. The problem is when I tried to get the row with the highest score, I couldn't find a way to resolve it.